The present invention relates to a flexure microactuator, and more particularly to a high resolution head positioning mechanism having a piezoelectric element for moving a flexure carrying a slider to selectively move the head on the slider radially with respect to a rotatable disc.
The density, or radial spacing, between concentric data tracks on magnetic discs continues to increase, requiring greater precision in head positioning. Conventionally, head positioning is accomplished by operating an actuator arm with a large-scale actuator motor, such as a voice coil motor, to position a head on a flexure at the end of the actuator arm. The large-scale motor lacks sufficient resolution to effectively accommodate high track-density discs. Thus, a high resolution head positioning mechanism is necessary to accomplish the more densely spaced tracks.
One promising design for high resolution head positioning involves employing a high resolution microactuator in addition to the conventional low resolution actuator motor, thereby effecting head positioning through dual-stage actuation. Various microactuator designs have been considered to accomplish high resolution head positioning. However, these designs all have shortcomings that limit the effectiveness of the microactuator. For example, where the microactuator was implemented directly on the slider, the complexity of slider design was increased and noise generated by the microactuator and by signal paths to it was induced into the head. New fabrication techniques had to be developed to integrate the slider and microactuator into a single structure. Where the microactuator was to be formed by thin-film wafer techniques onto the flexure, the entire flexure assembly had to be redesigned because the microactuator required a silicon substrate support and conventional gimbaling flexures were not constructed of silicon. Where the microactuator was implemented at the head mounting block (where the actuator arm connects to the head suspension load beam), high forces were required from the microactuator to move the mass associated with the head suspension at a speed (frequency) large enough to accommodate rapid track access. If the force was not great enough, the microactuator operated with lower natural frequency than was desirable, and track settling time was sacrificed. Therefore, the prior designs did not present ideal microactuator solutions.
There is a need in the art for a simple microactuator design to provide efficient high resolution head positioning in a dual-stage actuation system, that can be implemented by readily available manufacturing processes.